Tomographic imaging system

Abstract

In a system in which the tomographic image of an object under investigation is produced on the basis of the amount of absorption of radiation by the object when a source of radiation and a plurality of radiation sensitive detectors with the object interposed therebetween are rotated around the object, the output signal from at least one of the plural detectors is used to correct the radiation absorption amount. Another selected one of the plural detectors may be used for checking whether the object is positioned within a useful detection view.

What is claimed is: 
     
       1. A tomographic imaging system comprising: generating means for generating penetrating radiation toward an object under investigation;   detecting means including an array of radiation sensitive detectors for detecting the radiation from said generating means transmitted through the object and for providing an output indicative thereof, said detecting means including at at least one side of said detector array of radiation sensitive detectors, a checking detector being responsive to the radiation generated by said generating means which normally does not pass through the object under investigation for checking whether the object is positioned within a field of view of said detector array of radiation sensitive detectors, said checking detector providing an output indicative of the radiation generated which normally does not pass through the object;   means for comparing the output of said checking detector with a predetermined value for determining whether the object is positioned within the field of view of said detector array;   means for rotating said generating means and said detecting means while keeping a predetermined relative relationship in position with respect to each other; and   means for processing the output from said detector array to produce a tomographic image of the object.   
     
     
       2. A tomographic imaging system according to claim 1, wherein each radiation sensitive detector in said detector array is a gas chamber type of detector. 
     
     
       3. A tomographic imaging system according to claim 1, further comprising display means for displaying the output from said checking detector. 
     
     
       4. A tomographic imaging system according to claim 1, wherein a checking detector is provided at each side of said detector array. 
     
     
       5. A tomographic imaging system according to claim 1, wherein said detector array further includes a detector for producing an output signal for correction of the output of selected detectors of said detector array.